Analysis of the shelf life of chitosan stored in different types of packaging, using colorimetry and dentin microhardness.

OBJECTIVES: Chitosan has been widely investigated and used. However, the literature does not refer to the shelf life of this solution. This study evaluated, through the colorimetric titration technique and an analysis of dentin micro-hardness, the shelf life of 0.2% chitosan solution. MATERIALS AND METHODS: Thirty human canines were sectioned, and specimens were obtained from the second and third slices, from cemento-enamel junction to the apex. A 0.2% chitosan solution was prepared and distributed in 3 identical glass bottles (v1, v2, and v3) and 3 plastic bottles (p1, p2, and p3). At 0, 7, 15, 30, 45, 60, 90, 120, 150, and 180 days, the specimens were immersed in each solution for 5 minutes (n = 3 each). The chelating effect of the solution was assessed by micro-hardness and colorimetric analysis of the dentin specimens. 17% EDTA and distilled water were used as controls. Data were analyzed statistically by two-way and Tukey-Kramer multiple comparison (α = 0.05). RESULTS: There was no statistically significant difference among the solutions with respect to the study time (p = 0.113) and micro-hardness/time interaction (p = 0.329). Chitosan solutions and EDTA reduced the micro-hardness in a similar manner and differed significantly from the control group (p < 0.001). Chitosan solutions chelated calcium ions throughout the entire experiment. CONCLUSIONS: Regardless of the storage form, chitosan demonstrates a chelating property for a minimum period of 6 months.

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

This study evaluates the influence of root dentin treatment with NaOCl alone and combined with EDTA, with and without ultrasound activation, on the push-out bond strength (BS) of fiber-reinforced posts in weakened roots, cemented with RelyX or Panavia. The root canals of 42 maxillary canines were instrumented with Reciproc and 2.5% NaOCl. In the coronal 12mm of all canals, experimental weakening of the roots was produced by reducing dentin thickness with 2.44mm diameter diamond burs. The roots were assigned to 3 groups (n = 14) according to root dentin treatment: 2.5% NaOCl; 2.5% NaOCl + 17% EDTA; and 2.5% NaOCl + 17% EDTA, with solutions agitated using passive ultrasonic irrigation. After cementation of the fiber-reinforced posts the roots were divided in thirds. The first slice of each third was used for the push-out BS test, the second slice for confocal laser scanning microscopy and dentin microhardness (Knoop) analysis. Data were analysed by a two-way ANOVA and Tukey test (a = 0.05). NaOCl + EDTA provided highest BS values than NaOCl (p < 0.0001). Specimens cemented with Panavia presented significantly higher BS than those with RelyX in the three root thirds (p < 0.0001). The highest BS values occurred in the cervical third (p < 0.001). Ultrasound-activated NaOCl + EDTA promoted the greatest reduction in dentin microhardness, followed by NaOCl/EDTA and NaOCl. Ultrasonic activation of NaOCl and EDTA reduced root dentin microhardness, but did not improve the push-out BS of resin-based cements. Panavia presented higher BS than RelyX. RelyX was not influenced by the root dentin treatment protocols.

Evaluation of the chelating effect of chitosan solubilized in different acids.

AIM: This study aimed to compare, through dentin microhardness and colorimetric analysis, the chelating effect of 0.2% chitosan solubilized in different acids. MATERIALS AND METHODS: The second and third cuts of the cervical region of maxillary central incisors were divided into four quadrants, resulting in eight specimens, which were treated with 50 µL of solution for 5 min according to their group (n = 10): GI - 0.2% chitosan solubilized in 1% acetic acid; GII - 0.2% chitosan solubilized in 3.3% citric acid; GIII - 0.2% chitosan solubilized in 0.00145% hydrochloric acid; and GIV - 0.2% chitosan solubilized in 0.00112% nitric acid. A control was made from the chelating properties of the following acids: GV - 3.3% citric acid, GVI - 0.00145% hydrochloric acid, GVII - 0.00112% nitric acid, and GVIII - control (distilled water). Afterward, they were subjected to the Knoop microhardness tester with a load of 10 g for 15 s, resulting in three indentations of the root canal toward the cement. The measurements obtained were subjected to the one-way ANOVA test followed by Tukey's test (α =0.05). Subsequently dispensing the chitosan solutions, the same were subjected to colorimetric analysis. RESULTS: Chitosan solubilized in acetic acid, followed by chitosan in citric acid, provided a greater reducing effect compared to the other groups. Similar results were observed in the colorimetric analysis. CONCLUSION: It was concluded that the chelating ability of the chitosan solution solubilized in acetic acid is higher than solubilization in citric, hydrochloric, and nitric acids.

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

Abstract This study evaluates the influence of root dentin treatment with NaOCl alone and combined with EDTA, with and without ultrasound activation, on the push-out bond strength (BS) of fiber-reinforced posts in weakened roots, cemented with RelyX or Panavia. The root canals of 42 maxillary canines were instrumented with Reciproc and 2.5% NaOCl. In the coronal 12mm of all canals, experimental weakening of the roots was produced by reducing dentin thickness with 2.44mm diameter diamond burs. The roots were assigned to 3 groups (n = 14) according to root dentin treatment: 2.5% NaOCl; 2.5% NaOCl + 17% EDTA; and 2.5% NaOCl + 17% EDTA, with solutions agitated using passive ultrasonic irrigation. After cementation of the fiber-reinforced posts the roots were divided in thirds. The first slice of each third was used for the push-out BS test, the second slice for confocal laser scanning microscopy and dentin microhardness (Knoop) analysis. Data were analysed by a two-way ANOVA and Tukey test (a = 0.05). NaOCl + EDTA provided highest BS values than NaOCl (p < 0.0001). Specimens cemented with Panavia presented significantly higher BS than those with RelyX in the three root thirds (p < 0.0001). The highest BS values occurred in the cervical third (p < 0.001). Ultrasound-activated NaOCl + EDTA promoted the greatest reduction in dentin microhardness, followed by NaOCl/EDTA and NaOCl. Ultrasonic activation of NaOCl and EDTA reduced root dentin microhardness, but did not improve the push-out BS of resin-based cements. Panavia presented higher BS than RelyX. RelyX was not influenced by the root dentin treatment protocols.

Morphological Study and Analysis of Microhardness and Permeability of the Furcation of Maxillary Premolars.

The morphology, microhardness and dentin permeability of the furcation region of maxillary premolars were evaluated. Ten premolars were cut lengthwise and the furcation region was delimited. In one group (n=10) microhardness was measured in the buccal, central and palatal regions, in the outer middle and inner layers of the furcation, and in the buccal and palatal regions adjacent to the furcation. Knoop hardness was tested with 10 g load for 15 s. Data were analyzed statistically by ANOVA and Tukey-Kramer test (a=0.05). In the other group (n=10) confocal microscopy was used to study dentin morphology. Other 10 specimens were instrumented with ProTaper and immersed in 10% copper sulfate for analysis of permeability under light microscopy. About microhardness, there was no significant difference (p>0.05) among the buccal (39.9±3.1), central (39.5±4.4) and palatal (39.7±5.0) regions of the furcation, or between these regions and the adjacent buccal (39.1±5.8) and palatal (39.7±5.8) regions (p>0.05). The inner layer (42.3±3.7) had significantly higher microhardness (p<0.05) than the outer layer (37.1±3.9). There was a tendency of calcification of the dentinal tubules from the outer towards the inner layer. The percentage of stained area was 12.45±2.0%, restricted to the outer layer. The buccal, central and palatal regions of the furcation as well as the buccal and palatal adjacent regions had similar microhardness values. In conclusion, the inner dentin layer is harder than the outer dentin layer. The dentinal tubules are sinuous and intertwine towards the middle layer. Dye penetration is restricted to the outer layer.

Morphological Study and Analysis of Microhardness and Permeability of the Furcation of Maxillary Premolars

Abstract The morphology, microhardness and dentin permeability of the furcation region of maxillary premolars were evaluated. Ten premolars were cut lengthwise and the furcation region was delimited. In one group (n=10) microhardness was measured in the buccal, central and palatal regions, in the outer middle and inner layers of the furcation, and in the buccal and palatal regions adjacent to the furcation. Knoop hardness was tested with 10 g load for 15 s. Data were analyzed statistically by ANOVA and Tukey-Kramer test (a=0.05). In the other group (n=10) confocal microscopy was used to study dentin morphology. Other 10 specimens were instrumented with ProTaper and immersed in 10% copper sulfate for analysis of permeability under light microscopy. About microhardness, there was no significant difference (p>0.05) among the buccal (39.9±3.1), central (39.5±4.4) and palatal (39.7±5.0) regions of the furcation, or between these regions and the adjacent buccal (39.1±5.8) and palatal (39.7±5.8) regions (p>0.05). The inner layer (42.3±3.7) had significantly higher microhardness (p<0.05) than the outer layer (37.1±3.9). There was a tendency of calcification of the dentinal tubules from the outer towards the inner layer. The percentage of stained area was 12.45±2.0%, restricted to the outer layer. The buccal, central and palatal regions of the furcation as well as the buccal and palatal adjacent regions had similar microhardness values. In conclusion, the inner dentin layer is harder than the outer dentin layer. The dentinal tubules are sinuous and intertwine towards the middle layer. Dye penetration is restricted to the outer layer.

Resumo Estudou-se a morfologia, microdureza e permeabilidade dentinária da furca de pré-molares superiores. Dez pré-molares tiveram a porção oclusal da coroa e os terços radiculares médio e apical removidos. Cortou-se longitudinalmente o remanescente e delimitou-se a furca. As hemi-secções foram distribuídas em dois grupos. Num (n=10), mediu-se a microdureza nas regiões vestibular, central e palatina, nas camadas externa, média e interna e nas porções vestibular e palatina adjacentes à furca. Utilizou-se dureza Knoop, carga de 10 g por 15 s. Os dados foram analisados pelo teste ANOVA e Tukey-Kramer (a=0.05). No outro grupo (n=10) utilizou-se microscopia confocal para estudo da morfologia da dentina. Outros 10 espécimes foram instrumentados com Protaper e NaOCl a 1% e imersos em sulfato de cobre a 10% para análise da permeabilidade. Após preparo histológico os espécimes foram analisados em fotomicroscópio. Não houve diferença significante (p>0,05) entre a microdureza das regiões vestibular (39,9±3,1), central (39,5±4,4) e palatina (39,7±5,0), nem entre essas regiões e as adjacentes vestibular (39,1±5,8) e palatina (39,7±5,8) (p>0,05). A camada interna (42,3±3,7) é mais dura que a externa (37,1±3,9) (p<0,05). Há uma tendência dos canalículos calcificarem no sentido da camada externa para a interna. A porcentagem de área corada foi de 12,45±2.0 e restrita à camada externa. As regiões vestibular, central e palatina da furca, bem como as adjacentes vestibular e palatina apresentaram microdureza semelhante entre si. A camada interna apresentou-se mais dura que a externa. Os canalículos dentinários eram sinuosos e se entrelaçaram em direção à camada média. A penetração de corantes se restringiu à camada externa.

Geminated Maxillary Lateral Incisor with Two Root Canals.

This paper reports a case of gemination in a maxillary lateral incisor with two root canals and crown-root dilaceration. A 16-year-old male patient was referred for endodontic treatment of the maxillary left lateral incisor and evaluation of esthetic and functional complaints in the anterior region. The patient reported trauma to the anterior primary teeth. There was no spontaneous pain, but the tooth responded positively to the vertical percussion test and negatively to the pulp vitality test. Clinical examination showed esthetic and functional alterations and normal periodontal tissues. CBCT imaging confirmed the suspicion of gemination and crown-root dilaceration and also revealed the presence of two root canals and periapical bone rarefaction. The root canals were instrumented with Reciproc R40 and 1% NaOCl irrigation and were filled by lateral condensation of gutta-percha and AH Plus sealer. The tooth was definitely restored with composite resin to recover esthetics. Continued follow-up over 6 months has shown absence of pain or clinical alterations as well as radiographic image suggestive of apical repair.

The radix entomolaris and paramolaris: a micro-computed tomographic study of 3-rooted mandibular first molars.

INTRODUCTION: The morphology of the supernumerary third root (radix) in mandibular first molars was examined by micro-computed tomography (µCT) scanning. METHODS: Nineteen permanent mandibular first molars with radix were scanned in a µCT device to evaluate their morphology with respect to root length, root curvature direction, location of radix, apical foramen, accessory canals and apical deltas, and distance between canal orifices as well as 2- and 3-dimensional parameters of the canals (number, area, roundness, major/minor diameter, volume, surface area, and structure model index). Quantitative data were analyzed by 1-way analysis of variance and the Tukey test (α = 0.05). RESULTS: The mean length of the mesial, distal, and radix roots was 20.36 ± 1.73 mm, 20.0 ± 1.83 mm, and 18.09 ± 1.68 mm, respectively. The radix was located distolingually (n = 16), mesiolingually (n = 1), and distobuccally (n = 2). In a proximal view, most radix roots had a severe curvature with buccal orientation and a buccally displaced apical foramen. The spatial configuration of the canal orifices on the pulp chamber floor was mostly in a trapezoidal shape. The radix root canal orifice was usually covered by a dentinal projection. The radix differed significantly from the mesial and distal roots for all evaluated 3-dimensional parameters (P < .05). The radix canal had a more circular shape in the apical third, and the mean size of the minor diameter 1 mm short of the foramen was 0.25 ± 0.10 mm. CONCLUSIONS: The radix root is an important and challenging anatomic variation of mandibular first molars, which usually has a severe curvature with a predominantly distolingual location, and a narrow root canal with difficult access.

Morphology and microhardness of dentin at the furcation area of mandibular molars.

INTRODUCTION: This study evaluated dentin morphology and microhardness at the furcation area of mandibular molars. METHODS: Tooth segments of mandibular molars were embedded in resin blocks and bisected longitudinally (n = 20), and the furcation area was delimited by tracing 2 orthogonal lines from the most concave point of the outer surface of the furcation toward the mesial and distal canal entrances. In half of the specimens, Knoop microhardness was measured in 2 directions in the furcation area: vertically, parallel to the orthogonal lines and the bisector of the angle formed by them; and horizontally, in the outer (close to the pulp chamber floor), inner (close to the cementum), and middle dentin layers. Data were analyzed statistically by one-way analysis of variance and Tukey-Kramer test (α = 0.05). The other half of the specimens were examined by scanning electron microscopy to evaluate dentin morphology and trajectory of the tubules. RESULTS: No statistically significant difference (P > .05) was found among the mesial (46.5 ± 6.4), central (47.3 ± 8.1), and distal (49.7 ± 6.5) orthogonal lines. The inner dentin layer (51.7 ± 2.5) was statistically similar to the middle (46.3 ± 2.9) (P > .05), which was similar to the outer layer (41.4 ± 2.4) (P > .05). The inner layer was significantly harder than the outer layer (P < .05). The morphologic analysis revealed a tendency of calcification of the tubules from the outer toward the inner layer. CONCLUSIONS: Dentin microhardness at the furcation area is uniform in its 3 vertical axes, but the inner dentin layer is harder than the outer layer. The dentinal tubules follow a centripetal direction toward the inner layer, in which dentin is much more mineralized.